Kinetics based determination of trace amounts of silver at the excess of copper ions Original Research Article

The determination of silver traces, based on the catalytic action of Ag+ ions in the oxidation of salicylic acid by persulfate in the presence of 2,2′-dipyridyl as an activator, has been elaborated. The influence of several parameters, such as temperature, pH, salicylic acid concentration, persulfate concentration and 2,2′-dipyridyl concentration on the course of reaction has been investigated. The activation energies of the catalyzed (30.79 kJ mol−1) and non-catalyzed (44.77 kJ mol−1) processes were determined. Optimum conditions for the silver determination in the range of 4.3–38.8 ng cm−3 were established. The proposed method is more sensitive than atomic absorption spectrometry (AAS). The detection limit was 0.38 ng cm−3, so it was at least three orders of magnitude lower than that for the AAS method. The described method was used in the determination of the silver content in samples containing excess of copper and/or sulfate ions at concentrations of 8×10−6–2.4×10−2 M. The sulfate ions do not disturb the course of the reaction. The results of the determination of silver in a copper sheet by the proposed method were compared with the results of the analysis performed by AAS.